Given Corrine's actions in subsequent books, one could try to sympathise with her actions in the first. She essentially loses her husband and finds herself with four children to take care of - and she has no money. She could have taken other options, but it seems as if she's trying to avoid her children being split up (and the foster system of the day wasn't exactly great). As we never get her POV, part of her actions could be due to Olivia's influence. And it's clear that Olivia is very persuasive. While it almost certainly doesn't justify trying to poison her children, it does paint her actions into a greyer light than first seems.
On the flipside, it's also not hard to view Corrine as a superficial Drama Queen who never really loved her children. She's nice to them in the beginning because she has a life of leisure - with her husband paying for everything and children attending to her. But as soon as the luxuries are gone, she latches onto comfort rather than helping her children out. After all, there are plenty of valuables in Foxworth Hall that she could have stolen or sold off to get enough money to set herself and her children up. Her attempts at redemption could also be read as Never My Fault.
Author's Saving Throw: For those who find Chris being impossible to sympathise with after he rapes Cathy, the TV movie changes it to a consensual kiss and sex.
Fans are split on whether the eventual Brother-Sister Incest could have actually happened due to the Westermack Effect. Some choose not to believe in the effect, while others suggest that the Situational Sexuality was brought on by the fact that they're trapped together for so long.
There's also whether we can sympathise with Chris after he rapes Cathy. She claims she could have stopped him if she wanted to, but many find that to be victim blaming more than anything else. So it's up in the air whether Chris being a teenager who's gone through hell justifies the rape or not.
Corrine Foxworth is a greedy mother who doesn’t care at all about her children. Before the story began, Corrine ran away from her parents to marry her uncle and later had children with him. When she later hears the news of her dying father's inheritance money, the now-penniless Corrine takes her children to her father’s mansion after her husband’s sudden death. Because the only way she can inherit her father’s money is if she never had any children that he knew of, Corrine conspires with her abusive mother, Olivia Foxworth, to kill her children by locking them in a room, forbidding them from ever leaving, and slowly killing them off by both feeding them only cookies laced with an arsenic sugar, and simply starving them for months. While at the mansion, Corrine proceeds to indulge in her new lifestyle, and later decides to marry a young lawyer, showing that she never really cared for her previous husband. When her youngest child, Cory, starts getting sick from the cookies, Corrine feigns sadness and calls an ambulance. Instead, she disposes of Cory's body, hoping no one will find it. When her children manage to escape the attic and arrive at her new wedding, Corrine pretends that she doesn’t know them. Corrine is a horrible excuse of a mother fueled by greed and a desire to live a rich and luscious life.
The aforementioned Olivia Foxworth is a brutish religious fanatic who tortures and abuses her grandchildren for whatever she perceives as "sinful." She whips her daughter, Corrine, for running away with her husband’s brother, and locks her grandchildren up for being Corrine’s incestuous offspring. She helps Corrine with her plan to kill the children by feeding them cookies with arsenic sugar every day until they start feeling sick, as well as starving them. She does this not for her husband's inheritance money, but to make them suffer. She’s particularly cruel to her grandchildren, Cathy and Chris: when she sees them sleeping together in a bed, she smashes Cathy’s music box right in front of her; when she catches them innocently bathing together, she proceeds to lock Chris in a closet and abuse Cathy, chopping off a part of her hair. She then locks her grandchildren in the attic for months, which is far more cramped and unsafe to live in compared to their previous room. Sociopathic and cruel, Olivia proved to be just as evil as her daughter.
They Changed It, Now It Sucks: A rare example of the filmmakers themselves feeling this towards Corrine getting hung on her wedding day. The director refused to do it, so the studio had a second unit film the scene. Victoria Tennant also walked off the set, requiring a body double for the scene.
Values Dissonance: The movie ran into this when changing the setting. The book takes place in the 1950s, whereas the film is set when it was made (1986). The family is left destitute after Chris Sr, the sole breadwinner dies. Perfectly plausible in the 1950s, but odd in the 80s. Corrine being a housewife in the 80s is especially odd, even if she has four children. Also the Age Lift to make Chris and Cathy older makes one wonder why neither of them have after-school jobs or part time work.
Being extremely wealthy often results in holding traditional values where it's seen as "unseemly" for women to work, especially in old-money families like the Foxworths. Growing up in that wealth almost definitely means that Cathy and Chris might not have thought about work aside from a vague "after I graduate high school" concept, because they just didn't need to.